Distillation of tar



- May 1934' s. P. MILLER 1,95 5

DISTILLATION OF TAR v Original Filed Dec. 29, 1928 3 Sheets-Sheet 1 IINVENTQR MM 7M$MMY ZI ATTORNEYS y 15, 1934- s. P. MILLER 1,958,584

DISTILLATION OF TAR Original Filed Dec. 29, 1928 5 Sheets-Sheet 2ATTORNEY5 1 1934- s. P. MILLER Y 1,958,584

DISTILLATION OF TAR Original Filed Dec. 29, 19.28 3 Sheets-Sheet 3 YATTORNEYfi Patented May 15, 1934 DISTILLATION F TAR Stuart ParmeleeMiller, Scarsdale, N. Y., assignor to The Barrett Company, New York, N.Y.,

corporation of New Jersey Application December 29, 1928, Serial No.329,198 Renewed March 7, 1934 15 Claims.

This invention relates to improvements in the distillation of tar andthe production of pitch. It includes a new method of tar distillationand pitch production and an improved apparatus therefor.

GMore particularly, the invention relates to improvements in thedistillation of coal tar and the production of pitch at a coke ovenbattery.

In the ordinary operation of by-product coke ovens the gases produced bythe coking operation passfrom individual ovens through individual uptakepipes and goose-necks to a collector main common to a battery of ovens.The coke oven gases leaving the ovens at a high temperature are cooledto separate tar constituents therefrom, the tar constituents beingseparated partly in the collector mains and partly in subsequentcondensers.

Coal tar produced at by-product coke ovens is commonly shipped orconveyed to tar distillation plants where it is subjected todistillation for the recovery of coal tar distillates and the productionof pitch as a residue of the distillation.

The present invention enables the tar to be distilled and pitch produceddirectly at a coal distillation plant without the need of a. separatetar distillation plant and without transportation expense.

According to the present invention, the hot coal distillation gases, asfor example hot coke oven gases, as they come from the individual cokeovens, etc., are utilized 'for the distillation of tar and theproduction of pitch therefrom by bringing the tar into intimate contactwith the hot gases immediately after they leave the coke oven. Bybringing the tar directly into the hot coke oven gases at a hightemperature, the tar is effectively distilled with separation therefromof a greater or less amount of volatile oils, leaving a heavier tar orpitch as the product of the distillation. In 40 carrying out the presentinvention, the tar is brought into direct contact with the hot .coaldistillation gases and is distilled to pitch, but the tar and pitch areprotected from the high temperatures pertaining in close proximity tothe uptake pipes adjacent to the ovens in order to preventover-distillation or coking of such tar or pitch as might result fromsubjecting it to the intense heat radiated from these uptake pipes.

In the practice of the invention, several ovens of a coke oven batterymay be connected with distilling means for converting tar to pitch, andthe balance of the ovens may be connected in the usual way with acollector main and ordinary by-product recovery apparatus. As analternative and preferred method of operation, all of the ovens of thebattery may be connected with a collector main in the usual manner, andselected ovens of the battery may be equipped with additional uptakepipes, preferably located at the rear of the battery, and these uptakepipes will be connected with the tar distilling means of this invention.By the propermanipulation of valves in these additional uptake pipes andin the usual uptake pipes of these ovens which are connected with theordinary collector main, the gases from these ovens may be directed intothe ordinary collector main or they may be diverted into the tardistilling means.

In order to protect the product of the distil-' lation effected by thehot coal distillation gases, according. to this invention, from theintensive heat radiated from the uptake pipes, the stills are soconstructed that the pitch collecting means located at the bottom of thestills is protected from this heat, as by locating this pitch collectingmeans at some little distance from the uptake pipes. The pitch is thusprotected from localized overheating by the radiant heat from theseuptake pipes. The uptake pipes by which the ovens are connected to thedistillation means of this invention may be uptake pipes of the ordinarytype from which goose-necks resembling the ordinary goose-necks conductthe hot gases to the still or into a pitch receiver located at thebottom of the still. Each individual still may be equipped with anindividual pitch receiver or several stills may be equipped with acommon pitch receiver.

The hot gases enter the bottom of the distilling means which may be anordinary spray tower equipped at the top with a tar spray and at thebottoin with means for. admitting the hot gases and means forwithdrawing the pitch. Where more than one still is employed, the gasesleaving the tops ofthe stills enriched in volatile constituents areadvantageously collected in a common collector main and conveyed fromthere to condensers.

The gases leaving the coke ovens carry en trained solid and liquidparticles commonly known as tarfog.

Although a portion of these entrained particles may be removed from thegases in the still, due to contact with. the tar spray, where clean oilsare desired the gases leaving the stills and collected in the gascollector main are advantageously passed through an electricalprecipitator or other gas cleaning means a to remove entrainedparticles. 0n cooling the cleaned gases, clean oils are obtaineddirectly from the gases.

By the enrichment constituents by distillation of tar in per cent ofsolid and liquid impurities carried by the gases based on the vaporcontent is reduced. This, together with the fact that some entrainedparticles may be scrubbed from the gases during the distillation,permits the production of cleaner oils than ordinary by this process.

The enriched gases whether passed through cleaning apparatus or cooledwithout cleaning may be cooled fractionally to produce fractional of thegases in condensible condensates or a total condensate may be obtainedby cooling in a single condenser.

The melting point of the pitch produced by the distillation of the tarby the hot gases will depend upon the temperature to which the-tar ispreheated before it is sprayed into the gases, the temperature of thegases, the amount of tar sprayed into the gases, the size of the tarparticles, and the time during which the tar remains in contact with thehot gases. Where one passage of the tar through the still is notsuflicient to produce a pitch of the melting point desired, the pitchproduced may be recirculated through the still so that a higher meltingpoint pitch is obtained and by regulating the proportion of fresh taradmitted to the still and the proportion of pitch recirculated, themelting point of the final product can be controlled. The distillationcan further be regulated by admitting a small amount of water or ammonialiquor with the fresh tar in order to cool the gases and lessen thedistillation of the tar.

Where a common pitch collector is provided at the bottom of severalstills, an apron is advantageously provided at the bottom of each stillto prevent gases from the uptake pipes which enter the bottom of thestill from passing into the common pitch draw-oil.

In the drawings, various types of stills are shown. It is to beunderstood, however, that the invention is not limited to theillustrations given in the drawings.

In the drawings,

Fig. 1 is a plan view of a coke oven battery equipped with distillationmeans of this inven-' tion;

Fig, 2 is an elevation of the distillation means shown in Fig. 1;

Fig. 3 is'a sectional viewshowing the distillation means in its relationto the pitch collector main and the main for the enriched gases;

Figs. 4 and 5 are a plan view and elevation of a modified type ofapparatus; and

Figs. 6 and '7 are elevations of other modified types of apparatus.

In the drawings, 5 indicates a coke oven battery equipped in the usualway with uptake pipes 6, a collector main '7, a center box 8, andcrossover main 9, which may be of the usual type and are, therefore,shown schematically.

At the rear of the coke oven battery selected ovens are connectedthrough uptake pipes 10 to stills 11 and by proper manipulation ofvalves in the uptake pipes 10 and the uptake pipes 6 the gasesfrom theselected ovens may be passed through the stills or to the usualcollector main.

The stills may be ordinary spray columns equipped with spray means 12.at the top and connected at the bottom with a hot' pitch main 13 whichcollects the pitch resulting from the distillation in the variousstills. The gases pass from the ovens through the uptake pipes 10 intothe bottom of the stills and in passing up through the stills passcounter-current to the spray of tar the still, the

admitted through the sprays 12. The tar is distilled and the pitchproduced is drawn off the bottom of the stills through the aprons 14into the pitch main 13. The apron 14 seals the bottom of each still sothat the gases from each uptake pipe pass up through the correspondingstill 11 and do not pass out into the pitch main. By withdrawing thepitch through the pipe 14' a constant level of pitch may be readilymaintained within the main. The stills are provided with rodding holes15.

The pitch is drawn off from the hot pitch main through the pipe 16 intothe pitch container 1'1. Where one passage of the tar through the stilldoes not produce the desired distillation of the tar, the partiallydistilled tar drawn ofi from the stills through the main 13 and pipe 16into the receiver 17 may be in part recirculated through the stills bythe pump 18 and line 19 and blended with fresh tar admitted to thesystem through the pipe 20. The recirculated tar and fresh tar are thensprayed into the still, and the proportion of recirculated tar and freshtar is regulated in order to produce the desired distillation 'in thestill. The finished pitch may be withdrawn from the tank 1'? through thedraw-off 21.

The hot gases enriched in condensible constituents volatilized from thetar in the still are collected in the gas collector main 22. If cleanoil productsare desired from the operation, the hot gases are passedthrough the gas collector main to suitable gas cleaning equipment suchasan electrical precipitator. and the gases passing through the main 22are maintained. at a willciently high temperature to ensure the passageof desired oil constituents through the main 22 and the cleaningapparatus in vapor form, so that they are carried as vapors over intothe condensers where they are condensed by cooling in the usual manner.To maintain the gases at a high temperature the main 22, as well as thestill, etc., are advantageously well insulated.

Where cleaning is not necessary and the oils are to be recovered astarry oils, the gases may be cooled in the main 22 as with water orammonia liquor sprays. A pipe 23 is shown at one end of the main 22 forflushing the bottom of the main with a suitable medium to prevent theaccumulation or pitchy materials, etc., within the main where suchflushing is desirable.

Although other spray means may be employed such as a scrubber, etc., inthe drawings an electrical precipitator 24 is shown for cleaning thegases. The precipitator may be 01 the wellknown Cottrell type. Bysubjecting the gases to a silent electrical discharge as they passthrough the precipitator, entrained solid and liquid particles arethrown out of the gases and collect in the bottom 01' the precipitator.They constitute a pitch of higher or lower melting point, depend- 130cross-over main 9. Beyond the exhauster the 4 gases are treated for therecovery of ammonia, light oils, etc. In the condensers, the oilscarried by the gases in vapor form as they leave the precipitator arereduced to the liquid state and are recovered as clean oils and drawnoil into the 1m receivers 40. Where the gases are cooled below the dewpoint of the gases for ammonia liquor, the receivers 40 will be operatedas decanters for the separation of the ammonia liquor from the cleanoils.

Figs. 4 and 5 show modified apparatus in which the pitch from each still51 is separately collected in a separate receiver 50 instead of beingdrawn off into a common pitch main. The pitch from each still may bedrawn oif into a common storage tank 52, or separate pitch storage tanksmay be provided for the various stills. distillation is not attained inone passage of the tar through the still, the pitch may be recirculatedfrom the pitch receiver 52 by means of the pump 53 and the line 54.Fresh tar is admitted through the pipe 55. By properly adjusting theratio of the fresh tar and the partially distilled tar, the distillationcan be regulated to produce a desired pitch, which may be drawn oil fromthe pitch receiver through the draw-off 56. A clean out hole 57 is shownfor keeping the up-take pipe and goose-neck free from heavy pitch andcoke.

As an alternative arrangement, a small amount of water or ammonialiquormay be sprayed into the gases through 59 to regulate the temperature ofthe gases employed in distilling the tar sprayed into the gases at 58.The gases passing up through the lower portion of the still 60 afterpassing from the ovens through the uptake pipes 10 on coming in contactwith the tar sprays will distil the tar, and larger particles of sprayentrained in the gases will settle out as the gases pass up through thesettling chamber 61. The gases, more or less freed from entrained tarparticles, then pass over into the gas collecting main. Pitch residue iscollected in the receiver 62 which may be a receiver for the individualstill or a common pitch main.

The arrangement shown in Fig. 7 is a somewhat modified form in which thegases pass through the uptake pipe 10 into the still 65, where they meeta spray of tar from the pipe 66. The temperature of the gases may besomewhat regulated by spraying a small amount of water or ammonia liquorinto the gases from the spray nozzle 67. Vaporization of this spraycools the gases, and by regulating the spray the temperature of thegases with which the tar comes into contact may be more or lesscontrolled. The pitch re-- sulting from the distillation of the tar bycontact with the hot gases collects in the pitch receiver 68. Thisreceiver may be an individual receiver for the one still or may be avtar main connected with several stills. Where the distillation of tar isnot complete by one passage through the still, the partially distilledtar may advantageously be 'resprayed into the hot gases. By continuallydrawing oil a portion of the pitch and continuously adding a limitedamount of fresh tar to the cycle, a pitch of desired melting point maybe produced, and by regulating the temperature of the gases by admittinga fine spray of aqueous liquor through the spray nozzle 6'7, the degreeof the distillation may be limited and controlled and excessive cokingof the pitch may be prevented.

The various arrangements shown provide means for bringing tar intocontact with fresh hot coal distillation gases and converting the tarinto pitch. The tar is brought into contact with the fresh hot gasesalmost immediately after the gases leave the ovens. The tar is sprayedinto the gases and passes counter-current to the hot gases and isdistilled, the distillation residue be- Where complete 1 ing collectedat the bottom of the still in a reservoir protected from the intensiveheat radiating from the uptake pipe whereby excessive distillation ofthe pitch or decomposition of the pitch to produce coke is prevented.Although the in vention has been described more particularly as appliedto the operation of a coke oven battery, other coal distillation gasesmay be employed in carrying out the invention, as for example the freshhot gases from vertical gas retorts, etc.

I claim:

1. The method of distilling coal tar by hot coke oven gases andproducing pitch therefrom which comprises spraying a regulated quantityof the tar into fresh hot coke oven gases immediately after leaving theoven, thereby distilling the tar by contact with the hot gases andproducing pitch therefrom, and collecting the pitch resulting from thedistillation in a body out of indirect heat interchanging relation withthe stream of the hot gases thru the medium of the pipes conveying thegases directly from the ovens.

2. The method of distilling coal tar by hot coke oven gases andproducing pitch therefrom which comprises spraying a regulated quantityof tar into fresh hot coke oven gases immediately after they leave theovens, thereby distilling the tar by contact with the hot gases andproducing pitch therefrom, and collecting the pitch resulting from thedistillation at a point removed sufliciently from proximity to theuptake pipes of the ovens to prevent localized overheating of the pitchby the radiant heat from the uptake pipes to a temperature sufficient tocause objectionable decomposition of the pitch conveying the hot gasesfrom'the ovens to the still.

3. The method of distilling tar and producing pitch therefrom whichcomprises conveying fresh hot coke oven gases directly from a coke oveninto a still, passing the gases up through the still, spraying coal tardown through the still whereby the tar is distilled by the fresh hotgases and pitch is produced, spraying the walls of the still with tar toprevent the accumulation of pitch thereon, collecting the pitch from thewalls and spray deposited directly from the gases in a body out ofindirect heat interchanging relation with the stream of the hot gasesthru the medium of the pipes conveying the gases out of the coke ovens.

4. The method of distilling coal tar to produce pitch which comprisesconveying fresh hot coke oven gases directly from a coke oven into astill, passing the gases up through the still, spraying the tar into thegases as they pass up through the still, reducing the rate of flow ofthe gases to allow tar or pitch spray to settle from the gases,collecting pitch resulting from the distillation of the tar by contactof the tar spray with the hot gases, and cooling the gases leaving thestill to recover condensable oil constituents therefrom.

5. The method of distilling coal tar with hot coke oven gases to producepitch therefrom which comprises conveying fresh hot coke oven gasesdirectly from a coke oven into a still, passing the gases up through thestill, spraying the tar into the still and causing the tar to bedistilled by contact with the fresh hot gases, collecting partiallydistilled tar at the bottom of the still at a distance sufficient toprevent undesirable decomposition due to localized overheating of thepartially distilled tar by the radiant heat from the pipes conveying thegases from the ovens, and recirculating'a portion of the partiallydistilled tar through the still whereby it is subjected to fur- !-v therdistillation by the fresh hot gases and pitch is produced.

6. The method oiidistilling coal tar by hot coke oven gases whichcomprises conveying the fresh hot gases directly from a c 'ke oven intoa tower still, passing the gases. up through the tower still, sprayingthe gases with'a limited amount or an aqueous solution in the still andthen spraying them with the tar in the still whereby the tar isdistilled, and collecting distillation residue at the bottom of thestill.

'7. In combination with a coke oven battery, a tar still, an uptake pipeon top of one of the ovens of the battery and directly-Q connecting theoven with the tar still, a spray device for dispersing tar throughthegases in the still, and a pitch receiver at the bottom of the stillprotected from undesirable radiation of heat from the uptake pipe.

8. In combination with a coke oven battery, a tower still, a tar sprayin the top of the still and arranged to disperse a spray of tar throughthe gases in the still, an uptake pipe on top of one of the ovens of thebattery and directly connecting the oven with the bottom of the still, apitch receiver, and an apron at the bottom of the still dipping into thepitch receiver and thereby sealing the gases in the still against escapeinto the pitch receiver, the pitch receiver being situated at a distance'from the uptake pipe of the coke oven.

9. In combination with a coke oven battery, several tower stills, meansat the top of each still for spraying tar into each of the respectivestills, means for separately conveying gases from individual ovensdirectly to the respective stills, a common pitch main at the bottom ofthe stills, a common gas collector main for receiving from the stillsthe gases enriched in condensable constituents vaporized from the tar,and aprons on the bottom oi! each still to seal each still in the pitchflowing through the pitch draw-ofl.

10. In combination with a coke oven battery, a tower still, a spraydevice at the top of the still arranged to disperse a spray of tarthrough the gases in the still, an uptake pipe on top of one of theovens of the battery and directly connecting the still with the oven andconstructed so that no great temperature drop takes place in coke ovengases during their passage therethrough, a pitch receiver at the bottomof the still at a sufficient distance from the place where said gasconveying means connects with the oven to prevent localized overheatingof said pitch receiver by the radiant heat from said coke oven. 1

11. The method of distilling coal tar to produce pitch, which comprisesseparately conveying fresh hot coke oven gases from several ovens toseveral stills, passing the gases up thru the stills and spraying thetar down thru the stills whereby the tar is distilled by the hot gasesand converted to pitch, collecting the pitch from the several stills ina common pitch main out of indirect heat interchanging relation with thestream of the hot gases passing from the ovens to the stills whilekeeping the gases from the'several ovens distinct and then collectingthe gases from the various stills enriched in condensable oilconstituents vaporized from the tar.

12. In combination with a coke oven battery a tower still, means at thetop of the still arranged to disperse tar through the gases passing upthru the still and arranged to spray tar on to the walls of the still,an uptake pipe on top of one of the ovens of thebattery and directlyconnecting the oven with the still, a pitch receiver at the bottom ofthe still to collect spray which settles directly outof the gases intothe receiver and to collect tar which drains from the walls of the stilldirectly into the receiver, said receiver being at a sumcient distancefrom the place where said gas conveying means enters the oven to preventlocalized overheating of the receiver by the radiant heat from the gasconveying means.

13. In combination with a coke oven battery a tower still, means at thetop of the still for spraying tar into the still, a pitch receiver atthe bottom of the still and an uptake pipe on top of one of the ovens ofthe battery and directly connecting the oven with the top of thereceiver.

14. In combination with a coke oven battery a tower still, means at thetop of the still for spraying tar into the still, a pitch receiver atthe bottom of the still and an uptake pipe on top of one of the ovens ofthe battery and directly connecting the oven with the still near but notat the bottom thereof.

15. The method of distilling coal tar and producing pitch therefrom,which comprises spraying a regulated quantity of the tar into fresh hotcoke oven gases immediately after they leave the oven, therebydistilling the tar by contact with the hot gases and producing pitchtherefrom, passing the resultant mixture of gases and oil vapors througha settling zone whereby entrained particles of liquid are separated fromthe gases, collecting the pitch resulting from the distillation in abody out of indirect heat interchanging relation with the'stream of hotgases through the medium of the pipe conveying the gases directly fromthe ovens, then cooling the gases to recover condensable oils.

